His real name is Harvey Dent. He used to be Gotham City's District Attorney, and he had an alternate personality called Big Bad Harv, which often surfaced when Harvey got mad and pushed his “berserk button”. Later, after a mob boss named Rupert Thorne finds out about this alternate personality and threatened to blackmail him, Harvey was scarred by an explosion, and he became a maniacal, schizophrenic killer who could only make decisions with a coin toss. If his coin landed good heads up, he would do good. If it landed bad heads up, then he would do someone bad.